Gov. Parris Glendening announced that Maryland has scrapped its consideration of using “Site 104” in the Chesapeake Bay for the disposal of sediment dredged from shipping channels after the discovery of potentially harmful levels of toxics in the material.

Plans to put the dredged sediment at a deep area of the Chesapeake just north of the Bay Bridge, long known as Site 104, had drawn wide opposition from environmentalists and many area residents. But ruling out that low-cost option for sediment disposal could dramatically increase the cost of channel dredging.

“The best available science now indicates that proceeding with Site 104 could pose a serious threat to the health of the Bay,” Glendening said June 30. “It is clear that we must eliminate Site 104 from all further consideration. I have consistently indicated we will not do anything that would have a negative impact on the Bay.”

Earlier tests by the Army Corps of Engineers, which is developing an Environmental Impact Statement for the project, had indicated toxics were not a problem.

But recent analyses by the Corps found traces of PCBs, dioxin and pesticides in the shipping channel sediment. In lab tests, the sediment caused mortality among one of three species — Atlantic silversides — when exposed to the material.

Robert Summers, director of the Maryland Department of the Environment’s Technical and Regulatory Services Administration, said the contaminant levels are “extremely low.” He said the new findings do not reflect a change in sediment contaminant levels, but rather the use of new, more sensitive, testing procedures by the Corps.

The sediment poses little problem when left alone, but the process of releasing the dredged material at Site 104 would release the toxics in sufficient quantity that the Corps would require a “mixing zone.” Mixing zones are areas where chemicals are allowed to exceed water quality standards as they are diluted.

Although mixing zones are allowed by the Clean Water Act, the Chesapeake 2000 Agreement — signed only two days before the governor’s announcement — calls for a voluntary end of mixing zones over the next decade for chemicals that bioaccumulate or persist in the environment.

Summers said the state could not urge industries to phase out mixing zones, then exempt itself.

Opponents of using Site 104 immediately praised the decision.

“Today is a great day for the Bay,” said Theresa Pierno, executive director of the Chesapeake Bay Foundation’s Maryland office. “Governor Glendening did the right thing by terminating consideration of Site 104 as a potential disposal site for dredge material and, more importantly, by saying that open-water dumping, throughout Maryland’s waters is no longer an alternative for dredge disposal.”

U.S. Rep. Wayne Gilchrest, R-MD, also praised the decision, saying “The citizens who have been fighting this project have proven once again that you can fight City Hall and make a difference.”

Gilchrest said the Corps’ findings “raises questions about open water dumping and I’m glad the governor joins me in asking for a closer examination of what’s being dumped at other locations in the Bay.”

Now, most of the 4 million cubic yards of sediment dredged from the Baltimore shipping channels each year are likely to be transferred to island creation projects, such as Hart-Miller Island and Poplar Island, where sediments would be confined. That could carry a big price tag: Open water placement costs only about 20 cents per yard of dredged sediment, while island creation can cost several dollars per yard.

By ruling out Site 104, the state only has capacity for 8 years of sediment dredging, and it could create pressure for more island creation activities in the Bay.

And, the loss of capacity could jeopardize future plans to enlarge the Chesapeake & Delaware Canal to accommodate larger ships. Those plans had hinged heavily on the use of Site 104.

Port of Baltimore officials said they would immediately begin searching for new, environmentally acceptable, options for handling dredged material from both projects. Glendening expressed confidence that dredging issues could be solved in a way that protects the Bay, and the estimated 127,000 Maryland jobs related to port activity.

“I have always believed that a healthy Chesapeake Bay and a strong Port of Baltimore are not mutually exclusive,” Glendening said.